Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a beater bar for impact--crusher rotors, the
beater bar having on its rear side as seen in the direction of rotation of
the rotor surfaces by means of which it bears rearwardly and radially from
the interior against retaining parts fixed to the said rotor; and having, on
its front side, backing surfaces Eor wedges which keep the said beater bar
in engagement with the said retaining parts.
Reversible but not rotatable beater bars of this kind are known in
many designs They are particularly suitable for impact~crusher rotors con-
sisting of a plurality of discs secured to one axis and having peripheral
recesses into which the beater bars are inserted since, in rotors of this
kind, the beater bars are also exposed to wear between the discs on the inner
halves of their front sides, so that these surfaces cannot be used as backing
surfaces on the rear sides. Upon reversing the beaters, i.e, pivoting them
about a central transverse axis, the rear side remains at the back and the
front side at the front, but the inner half is now outermost and vice-versa.
A beater bar of this kind is disclosed, for example, in German
Disclosure Text 2 148 752, Like many other known beater bars, it has an elon-
gated cross section of constant width and is straight. Since to achieve a
satisfactory crushing action, the outer part of the front surface of the
beater bar which acts as the beating surface is preferably radial, or slopes
only slightly forwards, this design of beater bar produces a substantially
radial positioning of the beater bar as a whole in the recesses in the rotor
discs, The result of this is that, because of the wedges and pressure de-
vices arranged therefor, as seen in the direction of rotation of the rotor,
in front of the beater bars, these recesses must be bulged forwardly. This
produces a weakening of the rotor jaws gripping the beater bar from the front,
the front iaws being already weaker in that they are set back radially in
relation to the rear rotor jaws,
Since in beater bars of this kind, the backing surfaces for the
wedges also run radially, the complementary surfaces in the edge recesses
must also run obliquely inwards and forwards. This produces undercuts which
are difficult to machine, Furthermore, in order to achieve a beater bar of
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simple shape, the retaining parts secured to the rotor must be provided with
longitudinal ribs or grooves which are also difficult to machine. Finally,
in these known beater bars, the backing surfaces for the wedges are outside the
plane of symmetry of the beater bar, The result of this is that, after re-
versal of the beater bar, the wedges must bear against surfaces which have
already been subjected to at least a certain amount of wear, and are therefore
no longer accurately flat,
It is the purpose of the invention to provide a beater bar of simple
cross section, which can be clamped securely in a rotor, which itself also has
a small number of easily machinable surfaces, and which is moreover resistant
to bending.
According to the invention, there is provided a beater bar for impact-
crusher rotors, said bar being of reversible, elongated, mirror-symmetrical
cross section and of substantially constant width, and on its rear side, as
seen in the direction of rotation of the rotor, having surfaces by means of
which it bears rearwardly and radially from the in~erior against retaining
parts secured to the said rotor, and having, on its front side backing surfaces
for wedges which keep the said beater bar in engagement with the said retain-
ing parts, characterized in that the cross section has a plane of symmetry on
opposite sides of which are rearwardly-angled sections and in that the back-
ing surfaces for the wedges are located in the middle of the front side and
at right angles to the plane of symmetry of the beater bar,
The angling in the cross section provides a beater bar which is no
more difficult to cast than a bar having a continuous rectangular cross section,
whereas the profile of the rear side is suitable, as is, for backing-up, and
engaging behind, the rotor retaining parts. Furthermore, the angling in
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the cross section improves the resistance of the beater bar to bending, and
this is an advantage in the case of bars made from hard manganese steel, since
the surface of the bar in contact with the material being crushed tends to
stretch because of the material being initially soft, and this produces a
bending moment. On the front surface, it is easy to provide backing surfaces
for the wedges which, even if they are not in the form of cast reinforcements,
can easily be machined. During operation, these backing surfaces are com-
pletely covered by the wedges, they are not subjected to wear, and they may
therefore be used to back up the wedges even after the beater bar has been
reversed.
Since the backing surfaces slope in relation to the two outer sur-
/ p/ane
-L face parts of the front side, they are also at an angle to the radii in the
case of a beater bar incorporated with radial beating surfaces. This makes it
possible to select the wedges in such a manner that the surfaces of the rotor-
disc recesses against which the said wedges bear run parallel to the backing
surfaces of the retaining partsO This means that both surfaces can be mach-
ined at a single rotor setting.
Finally, the aforesaid slope of the backing surfaces for the wedges
produces a somewhat outwardly-directed direction of pressure which, in co-
operation with the backing surfaces for the retaining parts (which, for thepurpose of satisfactorily absorbing the shocks applied to the beater bar
during beating, should lie radially farther out) ensures very satisfactory
clamping of the beater bar.
Particularly good clamping of the beater bar occurs if the two sur-
faces of the rear side of the bar, which run at an obtuse angle towards each
other, extend for a certain distance beyond the plane of symmetry of the beater
bar and then run angularly backwards, thus producing two longitudinal grooves.
This makes it possible to provide the rotor retaining parts with an inner
surface running approximately peripherally, against which the beater bar bears
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radially from the interior. If casting inaccuracies make it necessary, the
cast longitudinal grooves are very easily processed by grinding, especially
since the surfaces to be ground are not large. Since the longitudinal grooves
are located on the rear side of the beater bar to which the pressure is ap-
plied, there is no objection to such grooves, especially since this side is
in full contact with its backing surfaces. The groove angle is preferably
9oo .
The inner regions, i.e. those adjacent the plane of symmetry,of
the surfaces of the rear side running towards each other at an obtuse angle,
are preferably slightly raised in relation to the outer regions and are
machined.
Although United States Patent 2,747,803 discloses a beater bar in
which the rear surface has a basic rearward buckle, the front side is basic-
ally straight. As a result of this, the beater bar has a very wide outer
surface, leading to heavy frictional wear. This also complicates the cross-
sectional shape. In this connection, the backing surface on the front side
of the beater bar is depressed, since it is impossible to machine such a sur-
face without special steps, as can be done in the case of the object of the
application. Instead, an intermediate piece must even be arranged between the
beater bar and the wedge, so that the wedge may move freely in relation to
the beater bar. The same applies to the beater bar according to German Patent
1~143,380, in which the front surface is also buckled forwardly.
Another advantage of the present invention over the above-
discussed publications results from the more advantageous location of the
center of gravity of the beater bar of the present invention. Because of the
~earwardly bent configuration of the beater bar of the present invention, the
center of gravity is located in the vicinity of the rear surfaces. As a
result thereof, due to the proportion of the moment arms, the wedges engaging
the front backing surface are virtually free of radial forces resulting from
centrifugal forces acting on the beater bar during the operation of the rotor.
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On the other hand, when the center of gravity is located further to the front
as is the case of United States Patent 2,747,803 on German Patent 1,143,380,
the wedges are subjected to much higner forces. The mounted position of the
beater bar of the present invention is also more advantageous inasmuch as the
radially inner section of the beater bar, that is, the rearward backing
surface thereof, engages more behind the backing retaining parts than is the
case in the beater bars of these references, even though the beating surfaces
of the present invention and of these publications may extend in the same
direction.
The invention also provides a rotor for impact crushers having
beater bars which, are of reversible elongated, mirror-symmetrical cross
section and of substantially constant width, each beater bar having on its
rear side as seen in the direction of rotation of said rotor, bearing sur-
faces which engage rearwardly and radially from the interior, against retain-
ing parts secured to said rotor, and on its front side, backing surfaces for
wedges which bear against said rotor and keep said beater bar in engagement
with the said retaining parts, characterized in that each beater bar has a
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cross-section having two rearwardly angled sections arranged on opposite sides
of a plane of symmetry said backing surface, on the front side of each beater
bar extending at right angles to the plane of symmetry thereof. Each bar is
clamped with a generally radially directed outer part, in such a manner that
the inner part is bent backwards in relation to the peripheral direction of
the rotor, since this makes it possible to shape in a satisfactory manner the
recesses provided at the periphery, the contours of which fit as closely as
possible around the parts used to clamp the beater bars and the beater bars
themselves, in view of the configuration of the jaws between which the said
beater bars are clamped. This is particularly important in the case of ro-
tors consisting of a plurality of rotor discs secured to a common axis.
Since the rotor surfaces between which the beater bars are clamped
require machining, it is desirable for the surfaces of the retaining parts
against which the rear of the beater bars bear, and the surfaces against which
the wedge surfaces bear, are parallel.
Figures 1 and 2 of the drawing illustrate diagrammatically cross-
R ~;e~S
sectional woavo of two embodiments of the beater bar according to the invention
incorporated into an impact-crusher rotor.
Beater bar 1 is incorporated into a rotor consisting of a plurality
of rotor discs 2 secured on a common axis (not shown). The discs have a
plurality of and, e.g. four, peripheral recesses 3, to the rear edges 4 of
which, as seen in the direction of rotation (arrow "a"), a retaining part in
the form of a supporting beam 5 is secured by welding. The front face of the
supporting beam, against which the rear of the beater bar bears, consists of
an outer part 6 extending approximately radially, and a part 7 at an angle
thereto and pointing inwardly to a greater or lesser degree.
Provided at the front edge 8 of recess 3 is a protective cap 9 en-
gaging with the edge and provided with a projecting edge 10 engaging in a
corresponding groove 11 in edge 8. The back of the cap carries a guide groove
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12 in which runs a wedge 13 which can be forced in a radially outward direc~
tion by means of a hydraulic ram 14 located at the bottom of recess 3.
Beater bar 1 has an angled, mirror-symmetrical cross section, the
plane of symmetry "b" of the bar passing through the axis shown in dotted
linest The rear face of the beater bar has two outer surface portions 15 and
two inner surface portions 16 adjacent the plane of symmetry, the latter
being slightly raised in relation to the outer surface portions 15 and being
machined, The front face of the beater bar has two outer surface portions 17
serving as beating surfaces, and a central surface portion 18 which lies at
right angles to plane of symmetry "b", and which serves as a backing surface
for wedge 13 and is also machined, Surface portion 18 is required only where
there is a wedge, i,e, in the vicinity of each rotor disc 2, Between the
discs, the outer surface portions 17 may converge towards the plane of
symmetry, as shown in dotted lines, Thus the wedge 13 can serve to prevent
the beater bar from being displaced longitudinally,
In the case of the beater bar illustrated in Figure 2, inner surface
portions 16 are extended beyond plane of symmetry "b", This produces two
grooves l9 which are defined outwardly by surfaces 20 by means of which the
beater bar bears radially, from the interior, against corresponding backing
surfaces 6, 7 of supporting beam 5, This design of beater bar permits a
simpler configuration of the supporting beam and improved retention of the
beater bar in the rotor. Since the grooves are located on the side of the
beater bar to which pressure is applied, the durability of the beater bar is
not impaired thereby,
However~ contrary to the graphic representation, outer surface portions
17 may run over the width of the beater bar only as far as surface portions 18
and, because of the improved machinability of the clamping surfaces, surface
portions 18 may be slightly raised in the width of the wedge,
